1. Field of the Invention
The present invention relates to a speed controller for motor, and more particularly, to a speed controller for motor preventing interference from reverse input, which is configured to rotate only in one direction when being driven in normal and reverse directions and has a function of preventing interference caused by a reverse input to prevent a shut-down of the operation of the speed controller by dispersing the reverse input and receiving only one direction input when rotating force is reversely input from an output side.
2. Description of the Related Art
Generally, a rotation device, such as a carrier or industrial machine, obtains driving force from a motor. In this case, the rotating force output from the motor may be transferred through an additional transmission. In other cases, a transmission may be provided in the motor itself so that the rotating force may be output directly or through an additional transmission.
In a case where a transmission is provided in a motor itself, two pawls 11 and 12 are generally mounted to a driving shaft 10 as shown in FIG. 1 so that any one pawl (constant speed pawl) 11 is directly restricted to an output unit 20 and the other pawl (speed changing pawl) 12 is restricted to the output unit 20 via a speed changing means.
More specifically, the constant speed pawl 11 bent clockwise is mounted to one side of the outer circumference of the driving shaft 10, and the constant speed pawl 11 is directly restricted at a portion 20a to the output unit 20. Also, the speed changing pawl 12 bent counterclockwise is mounted to the other side of the outer circumference of the driving shaft 10, and the speed changing pawl 12 is restricted at a portion 30a to a sun gear 30. Then, the sun gear 30 is engaged with a planetary gear 40, and the planetary gear 40 is engaged with the output unit 20.
Thus, if the driving shaft 10 of the motor (not shown) rotates in a normal direction, the constant speed pawl 11 is restricted to the output unit 20 to give a normal direction output, while if the driving shaft 10 rotates in a reverse direction, the speed changing pawl 12 is restricted to a speed changing means to give a speed-changed normal direction output to the output unit 20.
However, if the driving shaft 10 does not rotate in the transmission for a motor and rotation is reversely input from the output unit 20 by external force, the output unit 20 is rotated counterclockwise, so that the output unit 20 and the constant speed pawl 11 are restricted to each other first. Also, the output unit 20 rotating counterclockwise makes the planetary gear 40 rotate clockwise, the planetary gear 40 rotates the sun gear 30 counterclockwise, and then, the sun gear 30 is restricted to the speed changing pawl 12.
Thus, when the output unit 20 rotates counterclockwise, the constant speed pawl 11 and the speed changing pawl 12 are all restricted, so that the transmission does not work.